Method of developing two component diazo type copying material

ABSTRACT

A METHOD FOR DEVELOPING A TWO COMPONENT DIAZO TYPE COPYING MATERIAL CARRYING A LATENT IMAGE, WHICH COMPRISES EXPOSING THE LATENT IMAGE TO AMINE VAPORS GENERATED BY HEATING FINELY DIVIDED, POROUS, SUBSTANTIALLY DRY ADSORBENT PARTICLES HAVING ADSORBED AMINE THEREON, AND DIAZO DEVELOPING COMPOSITE PRODUCT USEFUL FOR SUCH METHOD.

0d. 1973 SHIGEAKI YOSHIDA ETAL v 3,764,326

METHOD OF DEVELOPING TWO COMPONENT DIAZO TYPE COPYING MATERIAL Filed April 5, 1972 United States Patent Ofice 3,764,326 Patented Oct. 9, 1973 3,764,326 METHOD OF DEVELOPING TWO COMPONENT DIAZO TYPE COPYING MATERIAL Shigeaki Yoshida and Takeshi Matsui, Tokyo, Japan,

assignors to Ricoh Co. Ltd., Tokyo, Japan Filed Apr. 5, 1972, Ser. No. 241,324 Int. Cl. G03c 5/18, 5/34 US. C]. 96-49 Claims ABSTRACT OF THE DISCLOSURE A method for developing a two component diazo type copying material carrying a latent image, which comprises exposing the latent image to amine vapors generated by heating finely divided, porous, substantially dry adsorbent particles having adsorbed amine thereon, and diazo developing composite product useful for such method.

. BACKGROUND OF THE INVENTION (a) Field of the invention The present invention relates to an improved method for developing two component diazo type copying material, wherein the latent image on the copying material is" exposed to amine vapors generated by heating finely divided, porous, adsorbent particles having adsorbed amine theeron.

(b) Description of the prior art The development of the latent image in two component diazo type copying material has heretofore been effecting by passing it through the atmosphere of ammonia gas. This method, however, is not satisfactory because of escape of the ammonia gas from the developing apparatus and/or the exhalation of the ammonia gas which adheres to the finished copy. This has required the development of special methods and apparatus to attempt to dispose of the irritating smell both from the original apparatus and the finished copy. The application of the method within a closed room and the like is very expensive. Besides, with the rigid enforcement of ecological regulations concerning the escape of ammonia or other noxious gases into the atmosphere, the employment of a developing method using ammonia gas is becoming more and more inadvisable.

A variety of new methods have been proposed to alleviate these difficulties but their application to the problems has proved to be very difiicult in practice. For example, the Japanese patent publications Nos. 16,114/ 1969, 25,222/1967, and 4,690/ 1962, and the US. Pat. No. 3,490,908, etc. disclose the process utilizing a roller interiorly containing a liquid alkaline substance such as monoethanol amine and outwardly provided with a porous layer such as a sponge. The roller presses onto the copying material having a diazo photosensitive layer to thereby saturated the sponge with the amine permeating from the inside and develop the latent image. These methods, however, have proved very difficult to control especially with respect to the quantity of liquid permeating the sponge due to the pressure of centrifugal force arising from rotation of the roller at the time of development. There are frequent occasions when either the liquid fails to permeate due to the pores of the sponge being too small or, because the pores are too large, it permeates excessively resulting in sticky copies. Even in the case of a sponge having pores of proper size, the processes are not free of trouble because with extended use the pores become clogged and retard the passage of liquid.

Other developing methods wherein an alkaline liquid is made to adhere to the roll and transferred to the diazo photosensitive layer, are described in Japanese patent publications Nos. 23,5 15/ 1970 and 5,348/ 1970, but these methods are also difiicult to control because of problems with controlling the adhesion of a fixed quantity of liquid to the roll. In case of the application of monoethanol amine as the alkaline reagent, for instance, when sufficient amounts of the alkaline liquid were made to adhere to the copying material to effect development, large quantities of the liquid would transfer and remain on the surface of the copying material because the liquid is relatively non-volatile and, moreover, does not permeate the copying material. As a result, the copy after development would feed sticky. Further, there was a danger of causing chemical burns through adhesion to the hands of persons who handle it. This holds true also in case of the aforesaid methods disclosed in the Japanese patent publication No. 16,114, etc., because these processes also work by the adherence of alkaline reagents to the surface of the copying material in the state of liquid per se.

Still another developing method has been proposed in which an image is developed utilizing a roller composed of an anhydrous powder developer; namely, a rollershaped product obtained by molding a molten mixture of urea, sodium acetate, polyamide or other resin and an alkaline substance such as monoethanol amine. The roller is made to directly contact the copying material. This method, however, is defective in that the powder developer is apt to come off the roller and adhere to the resulting copy, and, even in case the powder does not adhere to the copy, because of the surface of the roller and the inner part thereof being not linked together by means of continuous pores, the alkaline component in the inner part of the roller cannot be expected to come up to the surface following the exhaustion of the alkaline component existing on the surface and, consequently, succesive preparation of a number of copies is infeasible.

SUMMARY OF THE INVENTION The present invention provides methods and products which render it possible substantially to alleviate the aforementioned drawbacks in the prior art and to produce continuously a multiplicity of excellent copies. A particular advantage of the process is that it is a dry process.

In its broadest aspect the method of this invention is one in which the latent image in two component diazo type copying material is developed by exposing the diazonium compound and coupling compound components thereof to amine vapors which are sufiiciently alkaline to effect visible image forming reaction. The amine vapors are generated by heating a composition comprising finely divided, porous, substantially dry adsorbent particles upon which the amine has been adsorbed to a temperature of from about 30 C. to C.

An especially convenient procedure for carrying out the process of the invention is to superpose the diazo type copying material on a novel diazo developing composite product with the latent image facing the top layer of the said product and to bring the temperature to about 30 C. to 70 C.

The composite product comprises a top, amine vapor permeable layer which is substantially impervious to particles having a grain size greater than about 0.1 a

middle layer comprising fine, porous, adsorbent particles with a grain size greater than about 0.1;. and having the image developing amine adsorbed thereon. The bottom layer is substantially air and amine vapor impermeable. All components are, of course, chemically and physically inert with respect to the amine.

A number of practical diazo developing composite products can be devised. FIGS. 1 and 2 illustrate two such devices.

FIG. 1 is a schematic representation of a suitable product which may be utilized in practicing the present method by the use of a developing roller. FIG. 2 is a diagrammatic cross-sectional view of another such product in the form of a master sheet for use in development of latent images.

Referring to FIG. 1, the numeral reference 1 denotes a developing roller whose center is provided with an air-impermeable core 6 as a support for the porous adsorbent layer 2 comprising inorganic or organic fine powder with an amine adsorbed thereon.

The core may be constructed of any of a variety of metals, plastics and/ or gums which are inactive with amines, and, if necessary, it may be subjected to surface treatment so as to facilitate the stratiform adhesion of a fine powder with an amine adsorbed thereon onto the core.

The amines in the porous layer which is formed around the core 6 may include any of a wide variety of primary, secondary or tertiary aliphatic, aromatic and heterocyclic amines which can be adsorbed on the fine particles and desorbed therefrom as a vapor at the selected temperature, and are sufiiciently alkaline to effect reaction with the formation of a visible diazo image. The skilled artisan will have no difliculty in selecting a suitable amine or amines. Other functional groups may be present on the molecule. Typically useful amines which may be mentioned by way of example include monoethanol amine, diethanol amine, triethanol amine, N-ethyl ethanol amine, diglycol amine, morpholine, and the like.

Many inorganic or organic adsorbents, which are inert with respect to said amines, are useful in this invention. Suitably they will be in the form of a powder having a mean grain size of 0.1-500 and preferably 1-200 Products of the type often used as carriers for catalysts including silica, alumina and acid clay; or magnetic substances such as Ni, Fe and ferrite; or resins such as polyvinyl chloride and polyvinylidene chloride, may be employed.

It is often useful in the formation of the dry developing products of this invention to dilute the amines with a diluent such as water, ethylene glycol, polyethylene glycol, etc. at a proportion of -200 parts of the diluent based on 100 parts of the amine.

The fine powder with an amine adsorbed thereon possesses sufficient viscosity, so that it adheres to the core of the roller in that condition. This viscosity will also aid in pressing the porous adsorbent into a coherent body which is, of course, still permeable to amine vapors. It may also be useful to employ adhesives such as polyvinyl alcohol, casein, starch, methyl cellulose, carboxymethyl cellulose, polyvinyl acetate emulsion, polyacrylic ester emulsion, polystyrene or methyl methacrylate-butadiene copolymer latex. In this connection, the thickness of the porous layer, which may be varied according to the number of copies to be obtained, is usually in the range of about 0.1-10 mm.

In FIG. 1, 3 denotes the amine vapor and air-permeable sheet or layer surrounding the porous layer 2. Suitable materials to constitute this sheet include inorganic or organic fibers which are inactive with amines and air-permeable. The function of the sheet is to prevent the particles of the middle layer from coming into contact with the latent image without at the same time preventing the passage of amine vapors. The pores of the top layer should be such that particles with a grain size greater than about 0.1 will be held back. The thickness of the sheet is from about 0.1-1 mm. To give concrete examples of applicable materials, there are fabrics made of silk, cotton, flannel, felt, nylon, polyvinyl chloride, glass fiber, etc. and gauzes made of various metals. Fabrics made of natural or synthetic fibers such as cotton or nylon are especially preferred.

In FIG. 1, 4 denotes a heating roller to come in contact with the developing roller 1 through the diazo copying material to be developed. This heating roller 4 accommodates a device (not shown) capable of raising the surface temperature thereof up to C. in order to accelerate the development and obtain a highly concentrated image. It is desirable to so devise that the heating roller 4 will come into contact with the aforementioned assembly by the copying material side and be disconnected from the developing roller 1, which is disposed above the roller 4, except for the time when the development is performed. The two component diazo type copying material is denoted by 5.

The device of FIG. 1 may be provided as one unitary device or as separate parts. In any event, it will be employed so long as sufficient amine is generated to develop the latent image. It may then be replaced in toto or the diazo developing product of FIG. 2 may be employed by winding around the core of the developing roller. This master sheet is composed of three layers, namely, an airimpermeable base 1 consisting of, for instance, an aluminium plate, a porous layer 1 with the aforesaid amine adsorbed thereon, and an air-permeable sheet 3'. This is, according to the present invention, the use of a developing roller as set forth above is not necessarily required: it renders it possible to perform the development through the process of superposing said master sheet 7 for use in development upon a copying material and applying heat to the resulting assembly by the copying material side thereof by employing the heating roller 4 or other heating means.

The amines employed in the present invention may be quite volatile and some of the most useful are even volatile at room temperature (about 20 C.). The vapor produced is normally heavier than air. However, inasmuch as this amine has been adsorbed onto a fine powder, it never escapes into the air even when the products are stored or utilized over a long period of time. Moreover,'since the layer containing the amine is porous and permeable to amine vapors, the products of the invention have the advantage that, even after consumption of the amine in the upper section of the porous layer they are still useful because the amine of the lower sections is successively transferred to the surface where it is utilized in the development of latent images until the alkaline component is substantially exhausted. The process of the present invention is, as set forth above, characterized by the fact that the amine contacts the latent image as a vapor and'not as a liquid. Therefore, the composite developing product is substantially dry to the touch, and the resulting copy is absolutely free from excess adhesion of the amine and resulting stickiness.

Since the adsorbability of the adsorbent particles used in this invention varies with the grain size, the ratio of the amine to powder can vary appreciably. Normally, useful results are obtained if the quantity of the amine adsorbed on 100 parts of the powder is from about 10-200 parts. For instance, 100 g. of fine silica powder having a mean grain size of 100/L can be made to adsorb about 200 g. of monoethanol amine. The powder thus made to adsorb the amine can be maintained in the state of dry powder. 7

The process of this invention is applicable to the develoment of all of the conventional types of two component diazo type copying material.

EXAMPLE 1 By making 160 g. of a mixed solution consisting of 120 g. of monoethanol amine and 40 g. 'ofethylene glycol adsorbs'sufficiently to 100 g. of fine silica powder having a mean grain size of 540g, a dry powder developer was prepared. By interposing this powder developer( the thickness of layer thereof: mm.) between an aluminium base and a 0.5 mm. thick flannel cloth, a developing sheet as shown in FIG. 2 was prepared. Through the process of superposing an appropriate original upon a two component diazo type copying paper comprising a diazo compound and a coupling component (a manufacture of K. K. Ricoh; trade name: 80R) and subjecting to exposure by means of the mercury-arc lamp of a copying machine (a manufacture of K. K. Ricoh; trade name: Model- OMII), a latent image was produced on said copying paper. When the thus processed photo-sensitive surface and the flannel surface of the foregoing developing sheet were put together and subjected to pressure by the use of a heating roller having a surface temperature of 70 C. on the copying paper side, there was immediately obtained a highly concentrated blue-colored image. The copy immdiately after the development was quite dry with no adhering matter thereon and was odorless. Further, when 200 sheets of similarly exposed copying papers were developed successively, there was observed little change in the concentration of the developed color.

EXAMPLE 2 By bringing the post-exposure copying paper employed in Example 1 into contact with a developing roller as shown in FIG. 1, which was provided with the outermost layer consisting of a 300 mesh wire gauze (made of brass and being 0.2 mm. thick) and contained therein 200 g. of fine silica powder with a mean grain size of 40-100n adsorbed 170 g. of a mixture containing 150 g. of monoethanol amine and 20 g. of water adsorbed thereon, and subjecting them to pressure by the use of a heating roller having a temperature of 40 C.-60 C. on the side of the copying paper, there was obtained a clear-cut developed image.

EXAMPLE 3 By thoroughly dispersing 100 g. of fine silica powder with a mean grain size of 510,u. having 120 g. of diglycol amine adsorbed thereon into 150 g. of 5% aqueous solution of polyvinyl alcohol, a viscous coating liquid was prepared. By applying this coating liquid onto an aluminium-paper laminate on its paper side so as to form a coating layer of about 1 mm. thick thereon, sticking a cotton cloth of 0.5 mm. thick onto the surface of this coating layer while in the half-dried state, and then drying this assembly thoroughly, a developing sheet was prepared. When the development was effected by applying the same procedure as that in Example 1 subsequent thereto, there was immediately obtained a highly concentrated blue-colored image.

EXAMPLE 4 When a fine alumina powder having an equal grain size was substituted for the fine silica powder with a mean grain size of 5-10p in Example 1, the same result was obtained.

EXAMPLE 5 When the development was performed by applying the same procedure as that in Example 3 except for the employment of a coating liquid having the following composition, a satisfactory result equal to that in Example 3 was obtained.

Compositi0n:' 'G. A fine powder of polyvinylidene chloride (with' a mean grain size of 5-10 1.) 150 Monoethanol amine 150 Polyvinyl acetate emulsion containing 50% of I solid matter) Polyethylene glycol 10 EXAMPLE 6 Test was conducted by applying the same procedure as that in Example 2 except for the employment of a powder developer having the following composition. The result was as good as that in Example 2.

Composition: G. A fine alumina powder (with a mean grain size Monoethanol amine Ethylene glycol 25 Water 20 What is claimed is:

1. A method of developing an imagewise exposed two component diazo type copying material having a photosensitive layer comprising a diazonium compound and an azo-coupler thereon which comprises superposing the copying material on a diazo developing composite product comprising a top, amine vapor permeable layer which is substantially impervious to particles greater than about 0.1;/. in grain size, a middle layer comprising fine, porous adsorbent particles greater than about 0.1 in grain size having an amine adsorbed thereon, said amine being capable of desorption as a vapor by heating said particles to a temperature of from about 30 C. to 70 C. and sufficiently alkaline to efiect visible image forming reaction between the diazonium compound and the azo coupler in said photosensitive layer to form an azo image in unexposed areas, and a bottom layer which is substantially air and amine vapor impermeable; said photosensitive layer being in contact with said top layer and heating said diazo developing composite product to a temperature of from about 30 C. to 70 C. to desorb said amine from said adsorbent particles as a vapor which contacts said photosensitive layer and develops it, all components of said top and bottom layers being substantially chemically and physically inert to said amine.

2. A method as defined in claim 1, wherein the grain size of said fine powder is in the range of 0.1500,u., the thickness of the middle, porous layer is in the range of 0.1-10 mm. and the thickness of the bottom layer is in the range of 0.1-1 mm.

3. A method as defined in claim 1, wherein said diazo developing composite product is in the form of a roll.

4. A method as defined in claim 1, wherein said diazo developing composite product is in sheet form.

5. A method as defined in claim 1, wherein the amine is adsorbed to the fine, porous particles to the extent of 10-200 parts per 100 parts of said particles.

6. A method as defined in claim 1, wherein said amine is a member selected from the group consisting of monoethanol amine, diethanol amine, triethanol amine, N-ethylethanol amine, diglycol amine and morpholine.

7. A method as defined in claim 1, wherein said amine is diluted with from about 0 to 200 parts of diluent per 100 parts of the amine.

8. A method as defined in claim 7, wherein said diluent is a member selected from the group consisting of water, ethylene glycol and polyethylene glycol.

9. A method as defined in claim 1, wherein said particles are members selected from the group consisting of silica, alumina, acid clay, Ni, Fe, ferrite and resin. 

